1. Field of the Invention
This invention relates to a thin film magnetic head having at least a reading magnetoresistive effective type thin film magnetic head and a method of manufacturing the same, particular a composite type thin film magnetic head in which a reading magnetoresistive effective type thin film magnetic head and a writing inductive type thin film magnetic head are stacked and supported by a substrate and a method of manufacturing the same.
2. Related Art Statement
Recently, with the development of surface recording density in hard disk devices, composite type thin film magnetic heads are required to have excellent characteristics.
Then, a composite type thin film magnetic head in which an inductive type thin film magnetic head for writing and a magnetoresistive effective type thin film magnetic head for reading is suggested and practically used. Although as the reading magnetoresistive element, a magnetoresistive effective type thin film magnetic head using a normal anisotropic magnetoresistive (AMR) effect has been generally employed, magnetoresistive effective type thin film magnetic heads using a giant magnetoresistive (GMR) effect able to obtain larger resistance variation ratio than the AMR element and three to five times as large output as the AMR element and a tunneling junction magnetoresistive (TMR) effect are developed.
In this specification, these AMR element, GMR element and TMR element are generically called as a xe2x80x9cmagnetoresistive effective type thin film magnetic headxe2x80x9d or a xe2x80x9cMR reproducing elementxe2x80x9d in brief.
The use of the AMR element enables a surface recording density of several giga bits/inch2 to be realized, and the use of the GMR element or the TMR element enables the surface recording density to be more enhanced. Such a high surface recording density can realize a hard disk having a large capacity of more than 10G bites.
Generally, a MR film is composed of a film made of magnetic material showing the magenetoresistive effect and has a single layered structure. On the contrary, the GMR film mainly has a multi-layered structure composed of some films. There are some kinds of mechanism to generate the GMR effect, and the GMR film has a different structure depending on the mechanism. Concretely, as the GMR film, a superlattice GMR film, a granular film and a spin-valve film are exemplified. Particular, the spin-valve film has a relatively simple structure, suitable for mass-production, and shows a large resistance variation by a weak magnetic field.
In this way, the reading magnetoresistive effective type thin film magnetic head capable of attaining a high surface recording density can be easily realized by using the GMR film instead of the AMR film. On the other hand, with the characteristics of the reproducing head being enhanced, the characteristics of the writing head is required to be developed. The development of the surface recording density requires an enhancement of a track density in a magnetic recording medium. Thus, a width of a write gap in an ABS has to be narrowed to a submicron order from a several micron order, and for realizing it, a semiconductor processing technique is employed.
FIGS. 1-8 shows successive manufacturing steps of a conventional normal composite type thin film magnetic head. In each figures, reference xe2x80x9cAxe2x80x9d depicts a cross sectional view of the thin film magnetic head perpendicular to an ABS, and reference xe2x80x9cBxe2x80x9d depicts a cross sectional view of the magnetic pole portion parallel to the ABS. The composite type thin film magnetic head in this embodiment has a reading GMR reproducing element on a substrate and a writing inductive type thin film magnetic head stacked on the reading element. Since in practically manufacturing a thin film magnetic head, many thin film magnetic heads are formed on a wafer at the same time, the end of each thin film magnetic head does not appear. However, in the above figures, the end of the thin film magnetic head is shown for clarifying the figures.
First of all, as shown in FIG. 1, an insulating layer 2 made of alumina (Al2O3) is formed in a thickness of about 5-10 xcexcm on a substrate 1 made of AlTiC, for example, on which a first magnetic layer 3 constituting one magnetic shield layer to protect the reading GMR element from an external magnetic field is formed in a thickness of 2-3 xcexcm.
Then, as shown in FIG. 2, a first shield gap layer 4 is sputterformed, of alumina, in a thickness of about 50-100 xcexcm, and thereafter a multilayered structure-magnetoresistive layer 5 constituting the GMR reproducing element is formed in a thickness of less than 10 xcexcm. Moreover, for forming the magnetoresistive layer 5 into a desired pattern, a photoresist layer 6 is formed on the layer 5. In this case, the photoresist layer 5 is formed to a shape for itself to be easily lifted off, for example, T-shape. Next, the magnetoresistive layer 5 is ion-milled through the photoresist film 6 as a mask, and thereby is formed in a desired pattern.
Then, as shown in FIG. 3, a first and a second conductive layers 7a, 7b are formed in a thickness of several ten nm by using the photoresist film 6 as a mask. The conductive layers 7a, 7b are composed of TiW/CoPt/TiW/Ta laminated body. Next, as shown in FIGS. 4 and 5, the photoresist film 6 is removed by a lift-off process. As shown in FIGS. 4B and 5, the one ends of the first and second conductive layers 7a, 7b are connected to the one ends of the magnetoresistive layer 5, respectively. Moreover, as shown in FIG. 5, the cross section in FIG. 4A is taken on the plane slightly approaching to the first conductive layer 7a, not the plane passing through the center of the magnetoresistive layer 5 and perpendicular to the ABS.
Subsequently, as shown in FIG. 6, renewedly, a second shield gap film 8 made of alumina is formed in a thickness of 50-150 nm to embed the magnetoresistive layer 5 into the first and second shield gap layers 4, 8, and a second magnetic layer 9 made of permalloy is formed in a thickness of 2-3 xcexcm. The second magnetic layer 9 work not only as the other shield to magnetically shield the GMR reproducing element with the above first magnetic layer 3, but also as one pole in the writing thin film magnetic head.
Then, as shown in FIG. 7, a write gap layer 10 made of nonmagnetic material, for example, alumina, is formed in a thickness of about 200-300 nm on the second magnetic layer 9 and thereafter an insulating layer 11 made of photoresist is formed, on the part for a thin coil to be formed, in a thickness of 1-2 xcexcm corresponding to a given pattern, on which a first layer-thin film coil 12 is formed in a thickness of 3 xcexcm, insulation-separated by the photoresist film 13. Moreover, the insulating layer 13 made of photoresist to cover the first layer-thin film coil 12 is flattened by thermal treatment, and thereafter a second layer-thin film coil 14 is formed in a thickness of 3 xcexcm so as to be insulation-separated and supported by an insulating layer 15 made of photoresist.
Then, the insulating layer 15 made of photoresist to cover the second layer-thin film coil 14 is flattened by thermal treatment, and thereafter as shown in FIG. 8, a third magnetic layer 16 is formed corresponding to a given pattern. Then, as shown in FIG. 9, an overcoat layer 17 is formed in a thickness of 20-30 xcexcm. The third magnetic layer 16 is made of a permalloy material or FeN material having a high saturated magnetic flux density.
Lastly, the side surfaces of the magnetoresistive layer 5 and the write gap layer 10 are polished to form an air bearing surface (ABS) 18 opposing to a magnetic recording medium. A GMR reproducing element 19 is obtained through the polishing of the magnetoresistive layer 5 during the manufacturing process of the ABS 18.
In this way, the composite type thin film magnetic head in which the magnetoresistive effective type thin film magnetic head and the inductive type thin film magnetic head are stacked can be obtained. In the magnetic head, the MR height MRH of the GMR reproducing element is defined as the distance between the ABS 18 and the edge of the magnetoresistive layer 5 opposite to the ABS, and the throat height TH of the inductive type thin film magnetic head is defined as the distance between the ABS 18 and the side edge in the ABS side of the insulating layer 11. In a practical thin film magnetic head, pads to connect the first and second conductive layers 7a, 7b connected to the thin film coils 12, 14 and the GMR reproducing element 19 electrically to outside are formed on the side of the substrate, but in the above figures, the pads are omitted.
Since in the above conventional composite type thin film magnetic head, the first and second conductive layers 7a, 7b connected to the magneto-resistive layer 5 is opposed to the first magnetic layer 3 constituting a bottom shield and the second magnetic layer 9 constituting a top shield via the remarkably thin shield gap film, the electrical insulation between the these conductive layers and these magnetic layers is unlikely to be maintained in a good condition. The low insulation of the shield gap layers 4, 8 can not give the conventional composite type thin film magnetic head a high process yield.
For enhancing the insulation of the shield gap layers 4 and 8, it is considered to increase their thicknesses. However, from the view of a thermal asperity brought about with the development of the characteristics of the magnetoresistive effective type thin film magnetic head, the thickness of the shield gap layer is required to be as small as possible. As a result, the insulation of the shield gap layer can not be developed by increasing its thickness.
That is, in the magnetoresistive effective type thin film magnetic head, for overcoming the thermal asperity of degrading its reproducing characteristic due to its self-heat generation in reproducing, it is required that the first magnetic layer 3 constituting the bottom shield is made of a magnetic material having an excellent cooling efficiency such as permalloy or sendust, and the first and second shield gap layers 4 and 8 are formed, of alumina, in an extremely thin thickness of 50-100 nm by sputtering, so that the shield gap layer can not have a thicker thickness.
Moreover, in the magnetoresistive effective type reproducing element like the GMR reproducing element 19, for increasing its output, the resistances of the first and second conductive layers 7a, 7b are reduced, which has an advantage of ironing out the thermal asperity as above-mentioned. For decreasing the resistances of the first and second conductive layers 7a and 7b, it is considered to increase their thicknesses. However, the magneto-resistive effective type reproducing element has to be miniaturized for obtaining a high surface recording density and realizing a high efficiency, and from its view, it is restricted to increase the thickness of the conductive layer.
For mitigating the thermal asperity, improving the insulation defect between the conductive layer 7a, 7b in the GMR reproducing element 19 and the first and second magnetic layers 3, 9, and reducing the resistances of the conductive layers, the FIG. 3 in U.S. Pat. No. 5,907,459 discloses that a conductive layer constituting a lead for a magnetoresistive element is formed in a thinner thickness in a magnetic pole portion nearby an ABS and in a thicker thickness in the area except the magnetic pole portion.
However, when the conductive layer is formed in a stepped structure, a second shield gap layer is not formed precisely on the conductive layer, so that good insulation for a top shield can not be obtained.
Moreover, for ironing out the above problems, the Patent Gazette suggests the structure in which a bottom shield is provided only nearby the ABS, and a thick conductive layer is formed in the backward of the ABS, its surface being flattened, and is connected to a magnetoresistive element via a thin conductive layer formed on the flattened surface. Since such a structure enables the surface of the conductive layer to be almost flattened without having the step as above-mentioned, even if the thickness of the top shield gap layer is made thinner, the insulation between the conductive layer and the top shield is not deteriorated. Besides, since the better part of the conductive layer can be formed thick, their resistance can be reduced.
However, the composite type thin film magnetic head disclosed in the U.S. Pat. No. 5,907,459 has the bottom shield only nearby the ABS, so that, can not have sufficient good magnetic shield effect. For reading output signals from a minute magnetoresistive element, the noise due to the external magnetic field generated from an inductive coil or a hard disk motor, etc. has to be reduced as small as possible, but in the case of forming the bottom shield only nearby the ABS, the noises can not be suppressed sufficiently and the reproducing signals can not be read precisely.
Furthermore, since a magnetoresistive film and the thick conductive layer are electrically connected each other via a thin, thus a large resistive conductive layer, the heat generation in the thin conductive layer is maintained unmitigated. Since the thin conductive layer is adjacent to the magnetoresistive film, the heat generation brings about large influences for the thin film magnetic head.
It is an object of the present invention to provide a composite type thin film magnetic head to iron out or mitigate the various problems in the above conventional composite type thin film magnetic head and to remove the thermal asperity by decreasing the thickness of the shield gap layer, besides, to enhance the insulation between the conductive layer and the shield in the magnetoresistive element and the reproducing characteristics by reducing the resistance of the conductive layer.
It is another object of the present invention to provide a method capable of manufacturing in a high process yield such a composite type thin film magnetic head having the above excellent characteristics effectively.
An exemplary thin film magnetic head according to the present invention can include a substrate made of an insulating material, a first magnetic member, supported by the substrate, constituting one shield in a magnetoresistive effective type thin film magnetic head, and a magnetoresistive layer formed so as to be embedded in a shield gap layer on the opposite surface of the first magnetic member to the surface thereof supported by the substrate. The exemplary magnetic head can also include a second magnetic member constituting the other shield of the magnetoresistive effective type thin film magnetic head on the opposite surface of the shield gap layer to the first magnetic member, and an electrical connecting member to connect the magnetoresistive layer to an external circuit, having a first and a second conductive layer extending in insulating separation between the substrate and the first magnetic member.
An exemplary composite type thin film magnetic head in which a reading magnetoresistive effective thin magnetic head and a writing inductive type thin film magnetic head are stacked can include a substrate made of an electrical insulating material, a first magnetic member constituting one shield in a magnetoresistive effective type thin film magnetic head, supported by the substrate, and a magnetoresistive layer formed so as to be embedded in a shield gap layer on the opposite surface of the first magnetic member to the surface supported by the substrate. The magnetic head can further include a second magnetic member constituting the other shield of the mangetoresistive effective type thin film magnetic head and one pole of the inductive type thin film magnetic head, formed on the opposite surface of the shield gap layer to the first magnetic member, a write gap film formed at least on the opposite surface to the shield gap layer of the magnetic pole portion in the second magnetic member, and a third magnetic member constituting the other pole of the inductive type thin film magnetic head, opposing to the second magnetic member via the write gap film in a magnetic pole portion including an air bearing surface, magnetically connected to the second magnetic member in a position apart from the air fearing surface. Additionally, the magnetic head may include a thin film coil, its part being arranged in insulating separation with an insulating material so as to pass through the closed magnetic circuit composed of the second and the third magnetic member, and an electrical connecting member for the mangetoresistive layer, having a first and a second conductive layers extending in insulating separation between the substrate and the first magnetic member.
In such a thin film magnetic head according to the present invention, since the first and second conductive layers constituting the better part of the electric connecting member to connect the magnetoresistive layer to the external circuit are positioned between the substrate and the first magnetic member constituting a bottom shield, the conductive layers are formed sufficiently thick to reduce their resistances. Besides, since the first magnetic member as well as the shield gap layer is intervened between these conductive layers and the second magnetic member constituting a top shield, the dielectric breakdown therebetween does not occur at all.
In the composite type thin film magnetic head according to the present invention, it is preferable to connect the ends of the pair of conductive layers in the magnetoresistive layer-side to the magnetoresistive layer via conductive plugs extending throughout the first magnetic layer member. Since the conductive plugs may be positioned near the both ends of the magnetoresistive layer, the resistance of the electrical connecting member for the magnetoresistive layer can be more reduced.
Moreover, the conductive layers and the conductive plugs are preferably made of a Cu material having a small resistance to be easily formed and processed. In addition, the conducive layer made of the Cu material preferably has a thickness of 0.5-1 xcexcm, and the conductive plug made of the Cu material, as well preferably 2-3 xcexcm, depending on the thickness of the first magnetic layer.
An exemplary manufacturing method of a composite type thin film magnetic head in which a reading magnetoresistive effective type thin film magnetic head and a writing inductive type thin film magnetic head are stacked on a substrate, can include the steps of forming a first and a second conductive layers constituting leads to electrically connected to a magnetoresistive element in the magnetoresistive effective type thin film magnetic head, corresponding to a give pattern, forming a first magnetic member constituting a bottom magnetic shield on the first and second conductive layers and on the part for the magnetoresistive element to be formed later, insulated from the first and second conductive layers. The method can further include forming the magnetoresistive element on the surface of the first magnetic member so that it may be embedded in a shield gap layer and its both ends may be electrically connected to the first and the second conductive layers, respectively, and forming, on the shield gap layer, a second magnetic member doubling as a top magnetic shield and the bottom yoke of the inductive type thin film magnetic head and a third magnetic member constituting a write gap layer, a thin film coil and a top yoke, and thereby the inductive type thin film magnetic head.
In an embodiment of the manufacturing method of the composite type thin film magnetic head according to the present invention, a first and a second conductive plugs are formed throughout the first magnetic member in the ends of the first and the second conductive layers to be electrically connected to the magnetoresistive element. Then, after the magnetoresistive element is formed, a first and a second drawing electrode layers to connect its both ends to the first and the second conductive plugs, respectively, are formed. Moreover, a third and a fourth conductive plugs are formed at the ends of the first and the second conductive layers in the opposite side to the ends to be electrically connected to the magnetoresistive element. Then, it is preferable that in forming the second magnetic member, openings are formed at the shield gap layer and through the openings, the first and the second conductive layers made of the same material as the second magnetic member are formed so as to be connected to the third and the fourth conductive plugs.
In another embodiment of the manufacturing method of the composite type thin film magnetic head according to the present invention, the step of forming the first magnetic member comprises the step of forming a first magnetic layer on an insulating layer to cover the surfaces of the first and second conductive layers and the substrate, and the step of forming the second magnetic member comprises the step of forming a second magnetic layer on the surface of the shield gap layer. Then, the step of forming the third magnetic member comprises the step of forming, on the surface of the write gap layer, a third magnetic layer having a magnetic pole portion opposing to the second magnetic layer via the write gap layer and to be magnetically connected to the second magnetic layer in the opposite side to an ABS.
In a further embodiment of the manufacturing method of the composite type thin film magnetic head according to the present invention, the step of forming the first magnetic member comprises the step of forming a first magnetic layer on an insulating layer to cover the surfaces of the first and second conductive layers and the substrate, and the step of forming the second magnetic member comprises the steps of forming a second magnetic layer on the surface of the shield gap layer and forming a first pole chip on the surface of the second magnetic layer. Then, the step of forming the third magnetic member comprises the steps of forming a second pole chip so as to oppose to the first pole chip via the write gap layer and forming a third magnetic layer magnetically connected to the second pole chip and magnetically connected to the second magnetic layer in the opposite side to the ABS.
In each of the above embodiments, the third magnetic layer may be formed so that its forefront may be exposed to or receded from the ABS.
In an embodiment of the manufacturing method of the composite type thin film magnetic head, the step of forming the thin film coil comprises the steps of forming a first layer-thin film coil within the thickness of the second pole chip, flattening the surfaces of the first layer-thin film coil and the second pole chip and forming a second layer-thin film coil on the flattened surfaces.
In another embodiment of the manufacturing method of the composite type thin film magnetic head according to the present invention, the step of forming the thin film coil comprises the steps of forming a first layer-thin film coil within the thickness of the first pole chip, flattening the surfaces of the first layer-thin film coil and the first pole chip, forming a second layer-thin film coil on the flattened surfaces so as to be accommodated within the thickness of the second pole chip and flattening the surfaces of the second layer-thin film coil and the second pole chip. In this case, the third magnetic layer is preferably formed on the flattened surfaces of the second pole chip and the second layer-thin film coil.